1. Field of the Invention
Described herein are compositions including heterocyclic organic compounds. More specifically, described herein are fused thiophene compounds, methods for making them, and uses thereof.
2. Technical Background
Highly conjugated organic materials are currently the focus of great research activity, chiefly due to their interesting electronic and optoelectronic properties. They are being investigated for use in a variety of applications, including field effect transistors (FETs), thin-film transistors (TFTs), organic light-emitting diodes (OLEDs), electro-optic (EO) applications, as conductive materials, as two photon mixing materials, as organic semiconductors, and as non-linear optical (NLO) materials. Highly conjugated organic materials may find utility in devices such as RFID tags, electroluminescent devices in flat panel displays, and in photovoltaic and sensor devices.
Materials such as pentacene, poly(thiophene), poly(thiophene-co-vinylene), poly(p-phenylene-co-vinylene) and oligo(3-hexylthiophene) have been intensively studied for use in various electronic and optoelectronic applications. More recently, fused thiophene compounds have been found to have advantageous properties. For example, bisdithieno[3,2-b:2′,3′-d]thiophene (1, j=2) has been found to efficiently π-stack in the solid state, possesses high mobility (up to 0.05 cm2/V·s), and has a high on/off ratio (up to 108). Oligomers and polymers of fused thiophenes, such as oligo- or poly(thieno[3,2-b]thiophene (2) and oligo- or poly(dithieno[3,2-b:2′-3′-d]thiophene)(1)
have also been suggested for use in electronic and optoelectronic devices, and have been shown to have acceptable conductivities and non-linear optical properties. Unsubstituted fused thiophene-based materials tend to suffer from low solubility, marginal processability and oxidative instability. Thus, there remains a need for fused thiophene-based materials having acceptable solubility, processability and oxidative stability.